Safety-tread.



No. 791,017. PATBNTED MAY 30, 1905.

T. P. FARMER. SAFETY TREAD.

APPLICATION FILED 116.22.1904.

U NITED LSrrrres Patented May 30, 1905.

PATENI? OFFICE.

THICODORIC l). FARMER, Ol? SOUTHVVES'I HARBOR, MAINE, ASSIGNOR. TO

PROTECTIVE '.lltEAl) COMPANY, OI" BOSTON, MASSAOIAIUSE'IIS, A OOR- PORA'IION OF MAINE.

SAFETY-TREAD.

SPECIFICATION forming part of Letters Patent No.

791,017, dated May 3o, 1905.

nppIieation led August 22, 1904. Serial No. 221,595.

"u /tU wlmmt .it innig concern:

Beit known that I, 'Inuopoau P. FARMER, of Southwest Harbor, in the county of Hark cock and State of Maine, have invented ccrtain new and useful Improvements in Safety- Treads, of which the following is a specification.

rIhis invention has relation to safety-treads of the character of that illustrated in Letters Patent No. 696,362, granted to me on March 25, 1902, and its lirst object is to provideeertain improvements thereon which are illustrated in the accompanying drawings, described in the following specilication, and pointed out with particularily in t-he claims.

In the manufacture of safety-treads suoli as referred to I lind that it is highly desi rable to provide means for insuring the locking ofthe soft-metal plug in the cavity adapted for its reception and, further, to lighten the weight of the base plate or web, so as to render it easier to handle and cheaper to manufacture. I further find it is highly desirable to protect the upstanding walls of the sockets at or near the edges of the base plate or web, so as to prevent their being worn away too rapidly. Therefore in the present invention I preferably employ a cast web in which the sockets for the antislipping material extend entirely therethrough, said sockets being provided with inwardly-projecting lugs so constructed as to prevent the plugs from being forced inward or outward, as the ease may be. I further provide the web with raised hard-metal portions the uppcrsurfaccs of which are substantially liush with the upper edges of the walls which partially form said sockets, so as to save said sockets from excessive wear.

Referring to the accompanying drawings, Figure 1 represents in plan view a safety tread embodying the invention. Fig. 2 repY resents a section on the line Q 2 of Fig. Fig. 3 represents a section ou the line 3 3 of Fig. 1. Fig. 4 represents a section on the line 4 4 of Fig. i. Fig. 5 represents in perspective view a portion of the tread, one et' the sockets being empty to show the interior construction thereof.- Fig. 6 represents a section through the web for the introduction of the antislipping material.

Referring to the drawings, e indicates a hard metallic web, preferably of cast-iron or cast-steel. It may be of any suitable length and width, so as to contain one or more rows of sockets. The said web is cast with a pluf rality of apertures Z), each aperture being encircled by an upstanding wall or annular Harige c. The said langes or walls all project upwardly from the face of the web, so that the socket is ot' the depth equal to the thickness of the weh plus the height of the walls which project upwardly therefrom. These sockets may beof any suitable shape, although I have illustrated them as being circular or round. The inner surfaces of the sockets are perpendicular to the plane of the web; but the outer surfaces of the walls c are preferably frusto-conical, as illustrated more particularly in Fig. 3, The said sockets are lilled with said antislipping material, such as so ft lead, with which they will be filled while in the molten state'or when pressed therein in sheet form. In practice the web is cast in the form herein described, and the lead plugs, which are of suitable shape, are placed loosely in the sockets, after which the plate with the plugs thereon is passed between rollers, which pr'ess the plugs into the sockets so as to lill the same, leaving the upper surfaces of each plug flush with the upper edges of the opstanding walls c. For the purpose of preventing the remoral of the plugs each of the sockets is formed with inwardly-projecting lugs d, of which there may be as many as desired. They may he set so closely together as to practicaily form a continuous ring, but I lind that two oppositely -disposed lugs are sullicient for the purpose. Each lug` iu plan view is substantially scmicircular, its upper surface being substantially in plane with the upper 'surface of the web, and it tapers downwardly and outwardly, as shown in Fig. 3, so that it is, as it were, undercut. These lugs forni locks, which, being surrounded by the material of which the plug is made, securely hold the plugs in place against removal. By thus forming the ings the casting of the web is facilitated, sinee by under-cutting said lugs the web mayY be the more easily withdrawn from the mold. Along the edges of the web are rows of wear-surfaces e, which are formed integrally with the web. As illustrated they are substantially triangular in plan View and are arranged between the sockets, their bases being coincident with the side edges of the web. The wear-Surfaces e are llush with the tops of the walls e to protect them against undue wear.

Haring thus explained the nature ofthe invention and described the wayin making and using the same, but without attempting to set forth all the forms in which it may be made or all the modes of its use` l declare that what I Claim isl. A safety-tread comprising a web having one or more sockets, there being an upstane ing wall around eaeh socket, and eaeh socket being formed with a plurality of inwardly projecting undercut lugs, in combination with antislipping plugs filling said sockets and locked in place by the said lugs, substantiallwr as described.

2. A safety-tread com prising a web having walls upstanding from the face thereof which form sockets for the reception of antislipping material and wear-surfaees arranged alonglr the edge of said web and alternating with the said sockets, substantially as described.

1n testimony whereof I have aixed my signature in presence of two witnesses.

THEODORE P. FARMER.

Witnesses:

MARCUS B. MAY, C. C. STECHER. 

